Developmental abnormalities induced by ionizing and nonionizing radiation

ABSTRACT Embryos are more susceptible to ionizing radiation than adults. Heterotopic gray matter was found in the brain of victims prenatally exposed to the atomic bomb. We reproduced this malformation in mice. Many cells in the ventricular zone, except for radial glial fibers, were destroyed by radiation. Following the proliferation of surviving cells, postmitotic neurons migrated to the cortical plate. Some neurons in areas missing radial fibers could not migrate and remained as heterotopic gray matter. On the other hand, there is no evidence of human congenital abnormalities caused by nonionizing radiation. Teratogenicity of microwaves in experimental animals is regarded as their thermal effect. However, some studies have reported effects of radio frequency and extremely low‐frequency electromagnetic fields on cell proliferation and differentiation.